Farming activity that involves moving heavy equipment over the land is somewhat at the mercy of the weather. A long period of heavy rain at harvest time will often make the ground conditions impossible for the equipment. A farmer can be forced to watch the ruin of a crop worth hundreds of thousands of dollars. These conditions are usually not regular enough to justify the expense of bulldozer-type vehicles, when compared to the cost of the conventional four-wheel farm tractor.
Attempts have been made to combine the economy of the usual tractor with an endless track system of modest proportions. This idea is excellent, but only on the assumption that the unit (a) performs well, (b) is easily attached to the tractor, and (c) can be made available at a reasonable cost. The unit should be readily removed so that it does not get in the way, or continue to be subject to wear when it is not needed. It has been recognized that the best approach to the design of these auxiliary traction systems is to locate the track units so that they remain elevated until the usual drive wheels begin to sink seriously into soft ground. This arrangement retains the tractor's ability to operate at higher speeds on the harder road surfaces. The present invention is directed at satisfying these requirements.